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Manuscript Title: COLRAD: a program to calculate population densities of the excited atomic levels of hydrogen-like ions in a plasma.
Authors: N.N. Ljepojevic, R.J. Hutcheon, J. Payne
Program title: COLRAD
Catalogue identifier: AATR_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 44(1987)157
Programming language: Fortran.
Computer: VAX 11/780.
Operating system: VMS V4.
RAM: 1850K words
Word size: 32
Keywords: Plasma physics, Atomic level population Densities, Fine structure levels In hydrogen-like ions, Collisional-radiative Ionization, Recombination rate Coefficients, Atomic process.
Classification: 19.1.

Nature of problem:
The program calculates atomic level population densities of hydrogen- like ions present as small concentrations in high temperature plasmas. Fine structure levels are resolved up to principal quantum number n=4. Collisional-radiative recombination and ionization rate coefficients are also calculated.

Solution method:
The rate equation method of Bates et al. and McWhirter and Hearn has been used. Rate coefficients are calculated as described in Ljepojevic et al..

Restrictions:
The calculation is restricted to hydrogen-like ions of nuclear charge Z where 2<=Z<=35. Fine structure level splitting is included for levels with principal quantum number n<=4, so that the input variable NSPLIT, identifying of the highest level where account is taken of the fine structure, must not be greater than 4. The values of electron temperature at which the program runs are restricted to 4000Z**2K or greater, (see section 3.7.1 of the Long Write-up. The electrons and heavy particles (protons and hydrogen-like ions) are assumed to have Maxwellian velocity distributions of the same temperature. The plasma is assumed to be homogeneous and optically thin for all spectral lines of the ion treated.

Running time:
Approximately 5 min on a VAX 780 for the test job. The running time depends strongly on the number of temperature and density values used.